Coaster brake



Dec. 28, 194s.

. M. KLEIN coAsTER BRAKE -Filed sepi.- 25, 1945 Gttorneg Patented Dec. 28, 1948 NITED STATES PATENT OFFICE coAsTEa BRAKE Mathias Klein, Hawthorne, N. J., assignor to Curtiss-WrightCorporation, a corporation of Delaware 9 claims. l

This invention relates to coaster brakes for A' bicycles and the like, and more particularly to an improved back-pedaling brake of the character wherein a pair of yieldable members are operable, respectively, to drive a Wheel through its hub, to brake the same against rot-ation or permit freewheel rotation thereof in resp-onse to the selective manipulation of the pedal crank.

The invention has particular reference to a pair of spring coupling members which are independently operable, one to couple forward pedal movement to a wheel hub through a sprocket, and the other, to brake the wheel hub upon` a rearward pedal movement, a prehensile clutch member being provided between said pair of coupling members adapted to receive torque indirectly upon rearward pedal movement whereby operation of the braking spring coupling member is initiated. The arrangement is such that upon cessation of forward pedal movement, as in coasting, the wheel hub rotates relatively to the spring coupling elements.

The invention has further reference to a pair of oppositely wound spring coupling members which are individually operable, one to couple forward pedal movement to a wheel hub through a sprocket, and the other, to brake the wheel hub upon a rearward pedal movement through said sprocket. The arrangement is such that the drive and brake spring members are preloaded in frictional end-to-end relation whereby the inner end of the drive spring is substantially held to permit the expansion or partial unwinding thereof for clutching engagement with the wheel hub, in response to forward pedal movement.

In a reverse or rearward pedal movement to braking position, the drive spring is contracted or wrapped out of substantial engagement with the wheel hub, and during such contraction, the brake spring is expanded into braking engagement with the wheel hub,in.part by reason of the frictional contact between the drive and brake spring.

The principal object of the invention is to provide an improved coaster brake mechanism which represents the acme of simplicity in that it is constituted by a relatively few simple Aparts which are reasonable in cost of manufacture and are assembled and lubricated.

Another object of the invention is to provide bination, and arrangement of parts, the novel features of whi-ch are set forth with particularity in the appended claims, the invention itself, however, 'both as to its organization and its method of operation, together with additional objects and advantages thereof, being best understood from the following description of a specific embodiment, when taken in connection with the accompanying drawing in which:

Figure 1 is a, plan sectional view of the improved coaster brake mechanism as `assembled in a wheel hub and the frame of a bicycle;

Fig. 2 is a sectional view taken on the line 2 2 of Fig. 1;

Fig. 3 is an elevational view of the prehensile clutch member per se; and

Fig. 4 is a fragmentary elevational view illustrating a modified form of the invention wherein the two main spring coupling members are preloaded in frictional end-to-end relation.

Referring to the drawing, wherein similar reference characters indicate corresponding parts throughout, the improved coaster brake mechanism comprises a cylindrical drive sleeve ID having a plurality of annular shoulders Il, I2 and I3 formed thereon with one end of the sleeve Iii), adjacent the shoulder I3, suitably screw threaded and provided with a drive sprocket I4 securely locked thereon and against the shoulder I3 by means of a ring nut I5.

rIhe drive sleeve I0 is further provided with complemental ball races I6 and I'l and with'a rectangular slot or recess I8 in the shoulder I2, the ball race I6 being formed between the respective shoulders I2 and I3, and the ball race Il within the counterbore I9 provided in the outer end of said drive sleeve as clearly shown in Figs. 1 and 2.

A coiled spring 20, adapted to function as a drive coupling or clutch member, and presenting convolutions of substantially rectangular cross section and in mutual contact, is provided on one end thereof with an angularly bent,klaterally extending hook 2l. As clearly shown in Fig. 2, the clutch spring 20 is positioned on the drive sleeve I0 in concentric, spaced relation with the an improved, simplified coaster brake mechanism vention resides in the novel construction, comj hooked end 2|, positioned in the slot or recess I 8 provided therefor in the aforesaid shoulder I2. The opposite or inner end 22 of the clutch spring 20 extends to a point substantially intermediate the ends of the sleeve Il), and terminates in a ground end face, which presents a surface normal to the outer periphery of said spring and utilizable for a purpose hereinafter described.

Further in accordance with the invention, a

prehensile clutch unit comprising a relatively short, cylindrical sleeve 23 with an annular flange 24 formed thereon and having one end portion of a relatively small spring 25 securely attached to said sleeve 23, is journaled on the drive sleeve I, in abutting relation with the aforesaid shoulder I I, for rotational movement relative thereto, the remaining portion oi the spring 25 being journaled normally, in free but close fitting relation on the circumference of the drive sleeve I beyond the shoulder I I. As in the case of the aforesaid clutch spring 2G, the convolutions ofthe spring 25 are also substantially rectangular in cross section and in mutual contact.

For a purpose to be hereinafter described; Athe annular ange 24, forming a part of the sleeve 23, is provided with a radially disposeddowel pin 2'6 projecting horizontally from one face of the saidl ange 24.

The flanged sleeve 23 is retained against lateral movement on the drivesleeve l0, away from the shoulder II, by means of asplit snap'ring 21 oecupying an annular groove A28 formed in the drive sleeve I0, with a non-metallic anti-friction washer 29 interposed between `the flange 24 and the snap ring v21. With thenprehensile clutch unit thus assembled onthe drive sleeve I0, the clutch spring 2B is preloaded to exert an axial thrust of substantially six ounces, more or'less, ,against the Aface of the annular ange 24 wherebyto substantially hold the innermost end convolutionfof the said spring ZIJ for a purpose'hereinafter, described.

The remaining reduced end portion ofthe drive sleeve I0, to the left of theaforesaid ,snappring 21, as viewed in Fig. 2 is preferably, although Vnot necessarily, increased to a diameter 'substantially equal to the external diameterV ofthe aforesaid spring 25 by means o'f a cylindrical s leevefpress fitted over the said reduced end portion of the drive sleeve I0 as clearly shown in 2,l

An additional spring 3|, presenting convolutions whichV spiral in a Adirection opposite to the convolutions of` the .hereinbefore described clutch spring 2D, and adaptedl to function as ya brake member, are also substantially rectangular in cross section and in mutual contact. The4 inner end face 32 of the brake spring 3| is also ground normal to the outer periphery thereof and, in addition thereto, is provided with` an aperture or hole 33^for the reception of the f'reeend portion of the do'wel pin 25, carried by the annular flange 24, whereby the inner end face of said brake spring is positioned in contacting engagement withthe annular flange 24 and is mechanically connected thereto as clearly shown iri'Fig. 2. The opposite outer end of the brake spring v3I is alsofangularly bent to provide a laterally extending hook 34 for a purpose hereinafter described. y

AAs clearly indicated on the drawing, the `clutch spring 2li and the brake 'sprin`g'3 I, are preferably, although not necessarily, leach provided with a plurality of staggered vtrai'rsverse grooves or notches 35 in the lexternal surface thereof whereby to provide sharp edges adapted for breaking through a lm of voil or other suitable vlubricant during operation thereof on the vrotatable inner surface of a wheel hub 36. 4 y

The cylindrical wheel hub 3d having a uniform c *internal bore of a diameter vslightly 4greater than the normal external diameter of the clutch and brake springs 20 and 31 respectively and provided with a ball race 31 substantially inwardly of each of its ends, is journaled on the drive sleeve I0 in concentric relation therewith by means of a plurality of anti-friction balls 4I between the external ball race I6 and one of the internai ball races 31 provided in the wheel hub 3S.

The drive sleeve I0 and Wheel hub St are journaled on an axle 38 provided with screw threads on each` of its ends. A cone bearing 39, provided with a ball race 4G, is on one end oi said axle in ,adjustable relation thereto and in cooperative relation with the ball race 3T in the adjacent end of the wheel hub 36, a plurality of anti-friction balls 4I being disposed between the respective ball races '31 and 40 to provide an annular ball bearing.

The cone bearing 39 is further provided with an angular slot ory recess 42 adjacent the ball race inland on a radius adapted to permit the free re- -ception of the laterally projecting end hook 34 of the brake spring 3 I, whereby the outer end of the .brake spring 3l is anchored.

frjlhe bearing 39 is also provided with a reduced inner end portion 43 which extends into the floating end of the drive sleeve It to provide a pilot bearing therefor, a relatively short shoulder 44 presenting la pair ofv spaced parallel flat surfaces being formed on the outer face oi the cone bearm ingk 3'9 for the reception of a torque arm 45 adapted to holdl the vsaid bearing 39 against rotation.

clearly shown in Fig. 2, theaxle extends concentrically lthrough lthe drive sleeve it in spaced relation andA with its threaded end extended beyond lthe counterbored end of said sleeve lil for the threaded reception of a bearing cone, provided with aba-'l1 racen. The race 41 cooperates with the internal ball race I1 and with a plurality of anti-friction balls 48 disposed between the respective ball races l 1 and 41 to provide an annular ball bearing.

As will be understood by those skilled in the art,l the 'improved coaster brake mechanism is attached to the forked ends 49 of a bicycle frame 50, forexamplaby means of the spacing Washers 5t, lock washersZ and threaded nuts 53, the aforesaid 'torque arm 45 being held on the outer shoulder 44 of the bearing cone 39 and spaced from the adjacent trame end 49 by one of the spacing washers 5I. The free end of the torque arm 45 (not shown) is secured to the bicycle frame 50. t In a modied form of the invention, illustrated in Fig. 4, the prehensile spring clutch unit journaledon the drive sleeve I 0in cooperative relation with the inner free vends of the Vclutch spring 2li and vbrake spring 3|, 'als shown in Figs. 1 and 2, maybe entirely dispensed with and the respective springs 20 and '3| preloaded in frictional end-to- 'end relation whereby the inner end of the clutch spring 20' is friction'ally heldv by the inner end of the brakes'pring 3| and thus permit the expansion or unwinding'of the clutch spring 24 into clutching 'engagement with the wheel hub 3S in response to clockwise rotation of the drive sleeve it through the sprocket I4.

In' a braking operation, the winding up or contraction of the spring '2'0 causes the innermost end convolution of the spring 20 to impart a rotational movement to .the innermost convolution of the brakeA spring 3i whereby the said brake spring is unwound or expanded into frictional engagement with the wheelhub 36, Otherwise, the opposite or outer ends of the springs 20 and 3l are anchored in the same manner asin'Figs. land 2.

Operation Assuming 4that the improved coaster brake mechanism forms a part ofa bicycle structure and that y'it is 'driva'bly eo'mec'ted tothe pedal sprocket by a sprcket'chain, as in Fig. 1, the operation of the said mechanism on the rear wheel hub in a forward pedaling operation is as follows:

From a state of rest, rotation of the conventional pedal sprocket in a forward or clockwise direction, causes rotation of the sprocket i4 by reason of the chain therebetween. Since the sprocket I4 is attached to the sleeve I0, the initial clockwise rotation of the sleeve l0 transmits torque to the anchored end 2l of the spring 20 whereby the convolutions thereof are expanded into locked frictional engagement with the wheel hub 36 with the result'that the said hub is driven forward in response to forward pedal movement.

At the beginning of the forward pedaling operation', the convolutions of the spring 20 immediately engage the hub 36 by reason of the fact that the ground external diameter of said spring is of the order of 3 or 4 thousandths of an inch less than the internal diameter of the hub 3B, and also by reason of the fact that the angularly formed inner wall defining the slot -I8, in part, exerts an end thrust on the spring 20 as the sleeve l0 begins to rotate in response to forward pedal movement. Thus, the frictional contact between the inner end of the spring 20 and the flange 2li is enhanced to hold the inner end of said spring during the application of torque to its anchored end 2l to Vexpand the same in response to forward or clockwise rotation of the sleeve lil.

During the aforesaid operation, the expansion of the spring 20, causes the oppositely wound brake Yspring`3| to remain in a contracted or nonoperative state by reason of the friction-slip engagement of the spring 2li with the annular iiange 24 tending to wind or contract the said brake spring 3|. Moreover, during this same operation, the flanged sleeve 23 and thev auxiliary spring 2.5 attached thereto, remain substantially stationary relative to the 4rotating sleeve l0 by reason of the fact that the clockwise or forward sleeve rotation, tends to unwind the spring 25 out of frictional contact with the drive sleeve lll.

In a wheel braking operation, the sprocket I4 is moved in a counter-clockwise direction, in response to a back pedaling movement to full breaking position. Consequently, the sleeve I0 is also partially rotated in a counter-clockwise direction. By reason of the fact that the spring 20 is anchored, at one end, to the sleeve Il), the counterclockwise rotation thereof -will wind or contract the convolutions of said spring substantially out of frictional contact with the hub 36.

Simultaneously with the above noted contraction of the spring 2|), the counter-clockwise rotation of the sleeve lil, also causes the prehensile spring 25, clue to its light frictional contact with the said sleeve, to wrap down on the said sleeve, because of the direction in which it is wound, in response to the counter-clockwise rotation of the cylindrical sleeve lll and thus transmit torque from the sleeve l0 through the iianged sleeve 23 to the brake spring 3|. The aforesaid counterclockwise movement of the flanged sleeve 23, by virtue of the mechanical connection between the ange 24 and the inner end of the brake spring 3 I, results in the expansion of the said spring into braking engagement with the wheel hub 36. Since the spring 3i is anchored at its outer end to the xed bearing cone 39, the spring 3l is eifective to brake the wheel hub 36 in accordance with the applied back pedaling pressure.

From the foregoing it will be readily apparent that in a coasting of free-wheel operation, the pedals are held stationary after a back pedal movement insufficient to cause the prehensile spring 25 to wrap down on the sleeve lil with the result that the clutch spring 2D is contracted at least to its normal diameter and thus permit the free rotation of the wheel hub 36. While the invention has been shown as applied toa wheel hub utilized in bicycle construction, other applications thereof are also feasible as, for example, in small power Winches and also in other mechanisms wherein a smooth clutching, and rie-clutching action between two relatively movable members is desirable. Y

4"vllthoughone specific embodiment of the invention is "shown and described, it is to be expressly understood that several modications thereof `are possible. The invention, therefore, is not to be'restricted except in so far as is necessitated by theprior art and by the scope of the appended claims.

What is claimed is:

1. In combination, a fixed member, a cylindrical hub, a cylindrical drive sleeve disposed between saidiixed member and said hub in concentric spaced relation, means journaling said hub and drive sleeve o n said xed member, means carried by said drive sleeve adapted to couple said sleeve to said hub upon rotation of said sleeve in one direction, additional means anchored with respect to saidfixed member and supported by said sleeve adapted to frictionally engage said hubI upon limited rotation of said sleeve in an opposite direction and prehensile means responsive to said last named rotation to engage said additional means with said hub.

gZIn combination, a xed axle, a cylindrical hub,'a cylindrical drive sleeve disposed between said axle and said hub in concentric spaced relation, means journaling said hub and drive sleeve on said axle, a pair of coiled spring members carried by said drive sleeve in end-to-end relation, one of said spring members being adapted to couple said sleeve to said hub upon rotation of said sleeve`in one direction, said other spring adapted to `frictionally engage said hub upon rotation of said sleeve in an opposite direction and prehensile means on said drive sleeve responsive to said last named rotation to engage said additional means with said hub.

f3. In combination, a iixed member, a cylindrical hub, a cylindrical drive sleeve disposed between said fixed member and said hub in concentric spaced relation, means journaling said hub and drive sleeve on said fixed member, means carried by said drive sleeve adapted to couple said sleeve to said hub upon rotation of said sleeve in one direction, additional means carried by said sleeve adapted to frictionally engage said hub upon limited rotation of said sleeve in an opposite direction, and prehensile means for transmitting torque indirectly from said drive sleeve to said second named sleeve carried means upon said rotation last named.

4. In a device of the character described, a fixed member, drive and driven members disposed one within the other in concentric spaced relation and journaled on said fixed member, a pair of expansible members carried by said drive member and individually operable to couple said drive member to said driven member, means for directly expanding one of said members into -engagement with said driven member upon rotation of said drive member in one direction, and means including a coiled spring one way clutch for indirectly expanding the other of said members into engagement with said driven member Z upon rotation of said drive member inv an opposite direction.

5. A hub driving. and braking mechanism com-- prising a xed axle, a. hub rotatably iieurnaled thereon,- a cvlindricalY sleeve having al drive sprocket secured on one end thereof journaled on said axle substantially within said huby for rotation themen/.ithV relative tosaid axle, a spring clutch including: an annular flange journaled on said sleeveintermediate its ends, a drive spring coiled about said sleeve with its inner'vend infrictional contact with said iiange and its outer end anchored to said sleeveffor rotation therewith, a stationaryr brake spring coiled about. said sleeve. with its. inner end secured on the opposite side of said fiange with itsv outer end anchored to a. fixed journaling means disposed on one end of said axle, said sleeve being operable to expand said drive spring into driving engagement with said hub upon clockwise rotation of` said: sprocket and tocontract said drive spring upon a limited counter-,clockwise rotation of saidsprocket whereby said clutch spring is wrapped down on said sleeve and saidflange rotated. to expand said brake spring into engagement with said hub.

6. A hub driving driving. and braking mechanism comprising a drive sleeve, a hub and a iixed axle, said sleeve being journaled within said hub and said sleeve and` hub. on said axle for rotation relative thereto, means including an annular flange. journaled on said drive sleeve,- an expansible member carried by said; sleeve with one end thereofv in frictional engagement withsaid flange and its opposite end anchored to said sleeve, a second expansible member positionedabout said sleeve. with its inner end secured to said ange and itsopposite end anchored to a bearing cone secured on one end of said axle, said sleeve being operable to expand said first named expansible member into driving engagement with said hub upon clockwise rotation of said sleeve, said first namedv expansible member operating to transmit a counterclockwise movement to said flange in response to limited' reverse movement of said sleeve whereby said second named expansible member is expanded into braking engagement with said hub. i

7. In a device of the character described, a fixed member, drive and` driven members disposed one. within the other in concentric spaced relation and journaled on saidxed" member, ex-

pansible members carriedby saidd-rive member and individually operable to couple said drive member Ato said driven member and to couple said driven member to said xed member respectively, means fordirectly expanding one of said members into engagement with said driven member upon rotation of said drive member in one direction, and means; for indirectly expanding the. other. ofjsaid members into engagement with said driven member upon rotation of said drive member in an opposite direction, both. of said last: named means being entirely independent of said driven member.

8; A coaster brake comprising a wheel hub, a fixed axle shaft, a. drive sleeve, oppositelyl wound friction springs adapted to frictionally engage the inner Wall ofV said barrel whenA expanded, -means for anchoring one end of one of saidl springs relative to said axle shaft, means for anchoring one end of' the other spring to said sleeve, meansfrictionally retarding' the other end of said last named spring upon rotation of said drive sleeve in one direction, and' means for positivelyl exnanding said; rst mentioned spring when rotation of; said drive sleeve is eiected in the other direction, said last named means including a friction coil spring adapted to grip said sleevewhen rotation is eiected in such' other direction.

9. A coaster brakev comprising a wheel hub, a fixed axle shaft, a drive s1eeveoppositely wound riction springs adapted to frictionally engage the inner Wall of said barrel when expanded, means for anchoringv the outer ends of said springs relative. to said xed axle shaft and drive. sleeve respectively, each spring being undery slightv axial compression derived from compression of the other, and one; way clutch meansA between said sleeve and the inner free end of the axle shaft anchored spring to apply expanding torsionupon rotaton of said sleeve inone, direction.

MATHIAS` KLEIN.

REFERENCES crrnn The following referencesv are of record in the me of this. patent:

UNITED STATES PATENTS Num-ber Name Date- 1-, l..49.149 OHoro et all Aug. 3, 1915 Schall Feb. 23, 1926 

